As shown in FIG. 1, an elevator lifting mechanism of the prior art comprises an oil pressure mechanism 1 capable of actuating an oil pressure cylinder 2 to move up and down. The oil pressure cylinder 2 is fastened at one end thereof with an elevator cab 3. The oil pressure mechanism 1 is provided with a pressure lowering valve 4, which is intended for use by a maintenance worker to cause the elevator cab 3 to descent slsowly at such time when the elevator is being serviced or stopped by the power outage.
It is very likely that the elevator cab 3 is stopped right between two floors by an incident or a power interruption. Under such a circumstance, a passenger who is trapped in the elevator cab 3 is often unable to activate the pressure lowering valve 4 to drive the elevator cab 3 to the safety.